The present invention relates to an improved delivery system for the administration of large-molecule pharmaceuticals, e.g. peptidic drugs, vaccines and hormones. In particular it relates to pharmaceuticals which may be administered by means of an aerosol into the mouth, for buccal or pulmonary application.
In spite of significant efforts in academic and commercial laboratories, major breakthroughs in oral peptide and protein formulation have not been achieved. Relatively little progress has been made in reaching the target of safe and effective oral formulations for peptides and proteins. The major barriers to developing oral formulations for proteins and peptides include poor intrinsic permeability, lumenal and cellular enzymatic degradation, rapid clearance, and chemical stability in the gastrointestinal (GI) tract. Pharmaceutical approaches to address these barriers, which have been successful with traditional small, organic drug molecules, have not readily translated into effective peptide and protein formulations. Although the challenges are significant, the potential therapeutic benefits remain high especially in the field of diabetes treatment using insulin.
Scientists have explored various administration routes other than the injection for proteins and peptides. Oral and nasal cavities have been of greatest interest to scientists. Both the oral and nasal membranes offer advantages over other routes of administration. For example, drugs administered through these membranes have a rapid onset of action, provide therapeutic plasma levels, avoid first pass effect of hepatic metabolism, and avoid exposure of the drug to hostile GI environment. Additional advantages include easy access to the membrane sites so that the drug can be applied, localized and removed easily. Further, there is a good potential for prolonged delivery of large molecules through these membranes.
The oral routes have received far more attention than has the other routes. The sublingual mucosa includes the membrane of ventral surface of the tongue and the floor of the mouth whereas the buccal mucosa constitutes the lining of the cheek. The sublingual mucosa is relatively permeable thus giving rapid absorption and acceptable bioavailability of many drugs. Further, the sublingual mucosa is convenient, acceptable and easily accessible. This route has been investigated clinically for the delivery of a substantial number of drugs.
The ability of molecules to permeate through the oral mucosa appears to be related to molecular size, lipid solubility and peptide protein ionization. Small molecules, less than 1000 daltons appear to cross mucosa rapidly. As molecular size increases, the permeability decreases rapidly. Lipid soluble compounds are more permeable than non-lipid soluble molecules. Maximum absorption occurs when molecules are un-ionized or neutral in electrical charges. Therefore charged molecules present the biggest challenges to absorption through the oral mucosae.
Most proteinic drug molecules are extremely large molecules with molecular weight exceeding 6000 daltons. These large molecules have very poor lipid solubility and are practically impermeable. Substances that facilitate the absorption or transport of large molecules ( greater than 2000 daltons) across biological membranes are known as enhancers, (Lee et al., Critical Reviews in Therapeutic drug Carrier Systems, 8, 91, 1991; Lee et al., Critical Reviews in Therapeutic drug Carrier Systems, 8, 115, 1991, 1992). Enhancers have been characterized as chelators, bile salts, fatty acids, synthetic hydrophilic and hydrophobic compounds, and biodegradable polymeric compounds.
Various mechanisms of action of enhancers have been proposed. These mechanisms of action, at least for protein and peptidic drugs include (1) reducing viscosity and/or elasticity of mucous layer, (2) facilitating transcellular transport by increasing the fluidity of the lipid bilayer of membranes, and (3) increasing the thermodynamic activity of drugs (Critical Rev, 117-125, 1991, 1992).
Many enhancers have been tested so far and some have found to be effective in facilitating mucosal administration of large molecule drugs. However, hardly any penetration enhancing products have reached the market place. Reasons for this include lack of a satisfactory safety profile respecting irritation, lowering of the barrier function, and impairment of the mucocilliary clearance protective mechanism. It has been found that some enhancers, especially those related to bile salts, and some protein solubilizing agents give an extremely bitter and unpleasant taste. This makes their use almost impossible for human consumption on a daily basis. Several approaches have been utilized to improve the taste of the bile salts based delivery systems, but none one of them are commercially acceptable for human oral consumption to date. Among the approaches utilized includes patches for buccal mucosa, bilayer tablets, controlled release tablets, use of protease inhibitors, buccally administered film patch devices, and various polymer matrices.
The basic problem associated with the above technologies is the use of large quantities of bile acids and their salts to promote the transport of the large molecules through membranes in the form of localized delivery system using patches or tablets. In spite of using protease inhibitors and polymer coatings the technologies failed to deliver proteinic drugs in the required therapeutic concentrations. Further, the problem is compounded because of the localized site effect of the patch which resulted in severe tissue damage in the mouth. Most attempts were made to deliver large molecules via the oral, nasal, rectal, and vaginal routes using single bile acids or enhancing agents in combination with protease inhibitors and biodegradable polymeric materials. However, it is extremely difficult to achieve therapeutic levels of proteinic drugs using these formulations. Single enhancing agents fail to loosen tight cellular junctions in the oral, nasal, rectal and vaginal cavities for a required period of time in order to permit passage of large molecules through the mucosal membranes without further degradation. This problem makes it impractical to use the above mentioned systems commercially.
Oral delivery offers a variety of benefits for systemic drug delivery. For example, it provides easy, non-invasive access to a permeable mucosa, which facilitates rapid drug absorption and a fast onset of action of the drug. In comparison to the GI tract and other organs, the buccal environment has lower enzymatic activity and a neutral pH.
In order to overcome the above mentioned problem of the bitter taste, irritation and the penetration of large molecules through the sublingual, buccal and GI tract mucosal lining, a system has now been designed where a proteinic drug is encapsulated in mixed micelles made up of a combination of enhancers.
A method of substantially overcoming the above disadvantages has now been found. The amount of physiologically peptide or protein in the compositions of the present invention is typically a quantity that provides an effective amount of the pharmaceutical or drug to produce the physiological activity (therapeutic plasma level) for which peptide or protein is being administered. In consideration of the fact that the bioavailability of any active substance can never be 100%, it is preferable to incorporate slightly larger amount than the desired dosage. It is believed that improvements in penetration and absorption of mixed micellar formulations can be achieved by administering the mixed micellar formulation with propellants such as tetrafluoroethane, heptafluoroethane, dimethylfluoropropane, tetrafluoropropane, butane, isobutane, dimethyl ether and other non-CFC and CFC propellants. Preferably they are delivered through metered dose spray devices. Metered dose inhalers are known and are a popular pulmonary drug delivery form for some drugs. The present formulation, including the propellant, is intended to improve the quality of absorption, stability and performance of many formulations. The compositions have been selected to give enhancement in the penetration through pores, and facilitate absorption of the drugs to reach therapeutic levels in the plasma.
One of the other benefits of using an atomizer or inhaler is that the potential for contamination is minimized because the devices are self contained.
Accordingly the present invention provides a mixed micellar aerosol pharmaceutical formulation and a propellant, comprising i) a proteinic pharmaceutical agent in micellar form, ii) water, iii) an alkali metal C8 to C22 alkyl sulphate in a concentration of from 1 to 20 wt./wt. % of the total formulation, iv) at least three micelle forming compounds selected from the group consisting of lecithin, hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid, glycolic acid, lactic acid, chamomile extract, cucumber extract, oleic acid, linoleic acid, linolenic acid, monoolein, monooleates, monolaurates, borage oil, evening of primrose oil, menthol, trihydroxy oxo cholanylglycine and pharmaceutically acceptable salts thereof, glycerin, polyglycerin, lysine, polylysine, triolein, polyoxyethylene ethers and analogues thereof, polidocanol alkyl ethers and analogues thereof, and mixtures thereof, wherein the amount of each micelle forming compound is present in a concentration of from 1 to 20 wt./wt. % of the total formulation, and the total concentration of micelle forming compounds are less than 50 wt./wt. % of the formulation, v) a phenolic compound selected from the group consisting of phenol and methyl phenol in a concentration of from 1 to 10 wt./wt. % of the total formulation, and vi) a propellant selected from the group consisting of C1-C2 dialkyl ether, butanes, fluorocarbon propellant, hydrogen-containing fluorocarbon propellant, chlorofluorocarbon propellant, hydrogen-containing chlorofluorocarbon propellant, and mixtures thereof.
In one embodiment, the alkali metal C8 to C22 alkyl sulphate is in a concentration of from 2 to 5 wt./wt. % of the total formulation.
In another embodiment, the alkali metal C8 to C22 alkyl sulphate is sodium lauryl sulphate.
In another embodiment, the lecithin is saturated or unsaturated, preferably selected from the group consisting of phosphatidylcholine, phosphatidyl serine, sphingomyelin, phosphatidylethanolamine, cephalin, and lysolecithin.
In yet another embodiment, at least one of the micelle forming compounds is selected from the group consisting of hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid, polidocanol alkyl ethers, trihydroxy oxo cholanyl glycine, polyoxyethylene ethers, triolein and mixtures thereof, the concentration such micelle forming compound being from about 1 to about 5 wt./wt. %.
Preferably, the ratio of proteinic pharmaceutical agent, e.g. insulin, to propellant is from 5:95 to 25:75.
In another embodiment, the propellant is selected from the group consisting of tetrafluoroethane, tetrafluoropropane, dimethylfluoropropane, heptafluoropropane, dimethyl ether, n-butane and isobutane.
In yet another embodiment, the mixed micellar pharmaceutical formulation and propellant are contained in an aerosol dispenser.
For insulin-containing and some other compositions, the composition may also contains at least one inorganic salt which opens channels in the gastrointestinal tract and may provide additional stimulation to release insulin. Non-limiting examples of inorganic salts are sodium, potassium, calcium and zinc salts, especially sodium chloride, potassium chloride, calcium chloride, zinc chloride and sodium bicarbonate.
It will be recognized by those skilled in the art that for many pharmaceutical compositions it is usual to add at least one antioxidant to prevent degradation and oxidation of the pharmaceutically active ingredients. It will also be understood by those skilled in the art that colorants, flavouring agents and non-therapeutic amounts of other compounds may be included in the formulation. Typical flavouring agents are menthol, sorbitol and fruit flavours.
In one embodiment the antioxidant is selected from the group consisting of tocopherol, deteroxime mesylate, methyl paraben, ethyl paraben, ascorbic acid and mixtures thereof. A preferred antioxidant is tocopherol.
In a preferred embodiment at least one protease inhibitor is added to the formulation to inhibit degradation of the pharmaceutical agent by the action of proteolytic enzymes. Of the known protease inhibitors, most are effective at concentrations of from 1 to 3 wt./wt. % of the formulation.
Non-limiting examples of effective protease inhibitors are bacitracin, soyabean trypsin, aprotinin and bacitracin derivatives, e.g. bacitracin methylene disalicylate. Bacitracin is the most effective of those named when used in concentrations of from 1.5 to 2 wt./wt. %. Soyabean trypsin and aprotinin also may be used in concentrations of about 1 to 2 wt./wt. % of the formulation.
The proteinic pharmaceutical agent may be selected from a wide variety of macromolecular agents, depending on the disorder to be treated, generally with molecular weights greater than about 1000 and especially between about 1000 and 2,000,000. Preferred pharmaceutical agents are selected from the group consisting of insulin, heparin, low molecular weight heparin, hirulog, hirugen, huridine, interferons, interleukins, cytokines, mono and polyclonal antibodies, immunoglobins, chemotherapeutic agents, vaccines, glycoproteins, bacterial toxoids, hormones, calcitonins, insulin like growth factors (IGF), glucagon like peptides (GLP-1), large molecule antibiotics, protein based thrombolytic compounds, platelet inhibitors, DNA, RNA, gene therapeutics, antisense oligonucleotides, opioids, narcotics, hypnotics, steroids and pain killers.
The present invention also provides a process for making a pharmaceutical composition suitable for delivery through transdermal membranes comprising the steps of:
a) mixing a proteinic pharmaceutical agent composition in an aqueous medium with an alkali metal C8 to C22 alkyl sulphate, and at least one micelle forming compound selected from the group consisting of lecithin, hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid, glycolic acid, lactic acid, chamomile extract, cucumber extract, oleic acid, linoleic acid, linolenic acid, monoolein, monooleates, monolaurates, borage oil, evening of primrose oil, menthol, trihydroxy oxo cholanyl glycine and pharmaceutically acceptable salts thereof, glycerin, polyglycerin, lysine, polylysine, triolein, polyoxyethylene ethers and analogues thereof, polidocanol alkyl ethers and analogues thereof, and mixtures thereof, to form a micellar proteinic pharmaceutical agent composition;
b) during step a) or after step a), adding at least one micelle forming compound, different from that added in step a);
c) during step a) or after step a), adding a phenolic compound selected from the group consisting of phenol, m-cresol and mixtures thereof; and subsequently
d) placing the formulation into an aerosol dispenser and charging the dispenser a propellant;
wherein the composition has at least three micelle forming compounds and the amount of the micelle forming compounds are each present in a concentration of from 1 to 20 wt./wt. % of the total formulation, and the total concentration of alkali metal alkyl sulphate and micelle forming compounds is less than 50 wt./wt. % of the formulation.
In one embodiment, the process comprises:
axe2x80x2) mixing the proteinic pharmaceutical agent composition in an aqueous medium with the alkali metal C8 to C22 alkyl sulphate and optionally at least one of the micelle forming compounds, to form a micellar proteinic pharmaceutical agent composition;
bxe2x80x2) slowly adding at least one of the micelle forming compounds, different from that added in step axe2x80x2), while mixing vigorously, to form a mixed micellar composition;
cxe2x80x2) mixing the mixed micellar composition resulting from steps axe2x80x2) and bxe2x80x2) with the phenolic compound; and subsequently
dxe2x80x2) placing the formulation into an aerosol dispenser and charging the dispenser a propellant.
In another embodiment, the process comprises the steps of:
axe2x80x3) mixing the proteinic pharmaceutical agent composition in an aqueous medium with the alkali metal C8 to C22 alkyl sulphate and optionally at least one of the micelle forming compounds, while mixing vigorously, to form a mixed micellar composition;
bxe2x80x3) mixing the mixed micellar composition resulting from step axe2x80x3) with the phenolic compound; and subsequently
cxe2x80x3) placing the formulation into an aerosol dispenser and charging the dispenser a propellant.
In a further embodiment, the alkali metal alkyl sulphate is sodium lauryl sulphate.
In yet another embodiment, the formulation has micelle forming compound combinations selected from the group consisting of sodium hyaluronate, monoolein and saturated phospholipid, ii) saturated phospholipid, monoolein and glycolic acid, iii) sodium hyaluronate, polyoxyethylene ether and lecithin, iv) polyoxyethylene ether, trihydroxy oxo cholanyl and lecithin, v) polidocanol 9 lauryl ether, polylysine and triolein, and vi) saturated phospholipid, polyoxyethylene ether and glycolic acid
The vigorous mixing may be accomplished by using high speed stirrers, e.g. magnetic stirrers or propellor stirrers, or by sonication.
In one embodiment, the mixed micellar formulation is formed by sonication of the aqueous micellar pharmaceutical agent composition in which one of the micelle forming compounds is lecithin.
The present invention also provides a metered dose aerosol dispenser with the composition of the present invention therein, in which an aqueous phase containing the proteinic pharmaceutical agent is substantially separated from a phase containing the propellant.
The present invention also provides a method for administering mixed micellar pharmaceutical formulations of the present invention, by means of shaking the aerosol dispenser in order to intermix the aqueous and propellant phases, and then spraying the intermixed composition into the mouth with a metered dose spray device.
The present invention provides an improved method for delivery of macromolecular (high molecular weight) pharmaceutical agents, particularly through the membranes in the mouth or lungs. The pharmaceutical agents cover a wide spectrum of agents, including proteins, peptides, hormones, vaccines and drugs. The molecular weights of the macromolecular pharmaceutical agents are preferably above 1000, especially between 1000 and 2,000,000.
For example, hormones which may be administered with the present invention include thyroids, androgens, estrogens, prostaglandins, somatotropins, gonadotropins, erythropoetin, interferons, interleukins, steroids and cytokines. Vaccines which may be administered with the present invention include bacterial and viral vaccines such as vaccines for hepatitis, influenza, tuberculosis, canary pox, chicken pox, measles, mumps, rubella, pneumonia, BCG, HIV and AIDS. Bacterial toxoids which may be administered using the present invention include diphtheria, tetanus, pseudomonas and mycobactrium tuberculosis. Examples of specific cardiovascular or thrombolytic agents include heparin, hirugen, hirulos and hirudine. Large molecules usefully administered with the present invention include monoclonal antibodies, polyclonal antibodies and immunoglobins.
As will be understood, the concentration of the pharmaceutical agent is an amount sufficient to be effective in treating or preventing a disorder or to regulate a physiological condition in an animal or human. The concentration or amount of pharmaceutical agent administered will depend on the parameters determined for the agent and the method of administration, e.g. nasal, buccal, pulmonary. For example, nasal formulations tend to require much lower concentrations of some ingredients in order to avoid irritation or burning of the nasal passages. It is sometimes desirable to dilute an oral formulation up to 10-100 times in order to provide a suitable nasal formulation.
The mixed micellar formulation may be prepared by mixing an aqueous solution of the pharmaceutical agent, the alkali metal C8 to C22 alkyl sulphate, at least three micelle forming compounds, and optionally the phenolic compound. The micelle forming compounds may be added at the same time or after addition of the alkali metal alkyl sulphate. Mixed micelles will form with substantially any kind of mixing of the ingredients but vigorous mixing is preferred in order to provide smaller size micelles.
In one method a first micellar composition is prepared which contains the pharmaceutically active agent and at least the alkali metal alkyl sulphate. The first micellar composition is then mixed with at least three micelle forming compounds to form a mixed micellar composition. In another method, the micellar composition is prepared by mixing the pharmaceutically active agent, the alkali metal alkyl sulphate and at least one of the micelle forming compounds, followed by addition of the remaining micelle forming compounds, with vigorous mixing.
The phenol and/or m-cresol may be added to the mixed micellar composition to stabilize the formulation and protect against bacterial growth. Alternatively, the phenol and/or m-cresol may be added with the micelle forming ingredients. An isotonic agent such as glycerin may also be added after formation of the mixed micellar composition. The formulation is then put into an aerosol dispenser and the dispenser charged with the propellant. The propellant, which is under pressure, is in liquid form in the dispenser. In the present invention, when the composition of the present invention is in a dispenser, the aqueous phase is separated from the propellant phase. Because there are two phases, it is necessary to shake the dispenser prior to dispensing a portion of the contents, e.g. through a metered valve. The dispensed dose of pharmaceutical agent is propelled from the metered valve in a fine spray.
The preferred propellants are hydrogen-containing chlorofluorocarbons, hydrogen-containing fluorocarbons, dimethyl ether and diethyl ether. Even more preferred is HFA 134a (1,1,1,2 tetrafluoroethane).
Although the present invention has such wide applicability, the invention is described hereinafter with particular reference to insulin and its analogues, which are used for the treatment of diabetes.
As indicated hereinbefore, the aerosol compositions of the present invention require that the pharmaceutical formulation be in mixed micellar form.
In the case of insulin, which is intended for administration through the mouth cavity, the first micellar solution may be made by adding water, and then hydrochloric acid (typically 5M) to powdered insulin, and then stirring until the powder is dissolved and a clear solution is obtained. The solution is then neutralized with sodium hydroxide. The sodium alkyl sulphate is added with low speed stirring, either alone or with at least one micelle forming compound. A typical concentration of sodium lauryl sulphate, as the sodium alkyl sulphate, in the aqueous solution is about 3 to 20 wt./wt. % of the solution. Typically, insulin is present in the micellar solution in an amount which will give a concentration of about 2 to 4 wt./wt. % of the final formulation.
The micellar solution so formed may then be mixed vigorously, e.g. by sonication or high speed stirring, to form a mixed micelle liposomal solution. Other micelle forming compounds may then be added. For example, one or more micelle forming compounds selected from the group consisting of lecithin, hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid, glycolic acid, lactic acid, chamomile extract, cucumber extract, oleic acid, linoleic acid, linolenic acid, monoolein, monooleates, monolaurates, borage oil, evening of primrose oil, menthol, trihydroxy oxo cholanyl glycine and pharmaceutically acceptable salts thereof, glycerin, polyglycerin, lysine, polylysine, triolein, polyoxyethylene ethers and analogues thereof, polidocanol alkyl ethers and analogues thereof may be added. The mixing may be done with a high speed mixer or sonicator to ensure uniform micelle particle size distribution within the formulation.
After forming the mixed micellar formulation, the phenol and/or m-cresol is added prior to charging the composition to an aerosol dispenser. As indicated above, other ingredients, such as isotonic agents, flavouring agents, anti-oxidants, salts, protease inhibitors or other pharmaceutically acceptable compounds may also be added. After the formulation is in the aerosol dispenser, the dispenser is charged with propellant in a known manner.
Each of the micelle forming compounds, when present, is in a concentration of from 1 to 20 wt./wt. % of the total formulation.
Preferred salts of hyaluronic acid are alkali metal hyaluronates, alkaline earth hyaluronates and aluminium hyaluronate. The preferred salt is sodium hyaluronate. The preferred concentration of hyaluronic acid or pharmaceutically acceptable salts of hyaluronic acid is from 1 to 5 wt./wt. % of the total formulation. An even more preferred range is from 1.5 to 3.5 wt./wt. % of the total formulation.
The specific concentrations of the essential ingredients can be determined by relatively straightforward experimentation. It will be understood that the amounts of certain ingredients may need to be limited in order to avoid compositions which produce foam when sprayed rather than forming a fine spray. For absorption through the oral cavities, it is often desirable to increase, e.g. double or triple, the dosage which is normally required through injection or administration through the gastrointestinal tract.
As will be understood, the amount of each component of the formulation will vary depending on the pharmaceutical agent and the site of application. Preferred formulations buccal application have the following combinations: i) sodium lauryl sulphate, polidocanol 10 lauryl ether, sodium oxo cholanyl glycine and lecithin; ii) sodium lauryl sulphate, polidocanol 10 lauryl ether, phosphatidyl choline, oleic acid; iii) sodium lauryl sulphate, polidocanol 10 lauryl ether, sodium hyaluronate and lecithin; iv) sodium lauryl sulphate, polidocanol 9 lauryl ether, triolein and polylysine; v) sodium lauryl sulphate, polyoxyethylene ether (10 lauryl), trihydroxy oxo cholanyl glycine and lecithin, and vi) sodium lauryl sulphate, polidocanol 20 lauryl ether, evening of primrose oil and lecithin.
The therapeutic compositions of the present invention may be stored at room temperature or at cold temperature. Storage of proteinic drugs is preferable at a cold temperature to prevent degradation of the drugs and to extend their shelf life.
It is believed that the mixed micelles of the present invention encapsulate molecules with a high degree of efficiency ( greater than 90% encapsulation). In general the size of the micelle particles in the mixed micellar composition is about 1 to 10 nm or less, and preferably from 1 to 5 nm. Such mixed micelles tend to be smaller than the pores of the membranes in the oral cavity or the GI tract. It is therefore believed that the extremely small size of mixed micelles helps the encapsulated molecules penetrate efficiently through the mucosal membranes of the oral cavity.
The desired size of aerosol droplets which are sprayed from the aerosol dispenser will depend, in part, on where the pharmaceutical is to be deposited. For example, for deposition in the lungs, particle sizes of less than about 5 xcexcm are preferred whereas for absorption in the buccal cavity of the mouth, particle sizes of about 6-10 xcexcm are preferred.
The amount of physiologically peptide or protein in the compositions of this invention is typically a quantity that provides an effective amount of the pharmaceutical or drug to produce the physiological activity (therapeutic plasma level) for which peptide or protein is being administered. In consideration of the fact that the bioavailability of any active substance can never be 100%, that is to say the administered dose of the active drug is not completely absorbed, it is preferable to incorporate slightly larger amount than the desired dosage.
It is believed that improvements in penetration and absorption of mixed micellar formulations are achieved by mixing the mixed micellar formulation with propellants such as tetrafluoroethane, heptafluoroethane, dimethylfluoropropane, tetrafluoropropane, butane, isobutane, dimethyl ether and other non-CFC and CFC propellants. Preferably they are delivered through metered dose spray devices. Metered dose inhalers are known and are a popular pulmonary drug delivery form for some drugs. One of the benefits of using an atomizer or inhaler is that the potential for contamination is minimized because the devices are self contained.
The present formulation, including the propellant, is intended to improve the quality of absorption, stability and performance of many formulations. The compositions have been selected to give enhancement in the penetration through pores, and facilitate absorption of the drugs to reach therapeutic levels in the plasma.
Administration of the formulation into the buccal cavity is by spraying the formulation into the mouth, without inhalation, so that the droplets stay in the mouth rather than be drawn into the lungs.